Hi all,
I have built several drum modules, +/-12v and 5v Hagiwo things, but mixing them is a pain.
I currently use Sam’s Super Simple Mixer but they seem to influence the outputs of each other, and cancel each other out at times.
I tried adding a opamp buffer before the mixing stage for each channel (6) and then a separate module to up the gain of quieter modules but neither has helped.
Should I try using a diode (1n4148) for each channel like in the megadrone schem?
Thanks in advance for your time, have tried to search for drum machine mixers but not seeing any different ways. Anyone here have a new schem to try?
A mixer with high impedance inputs (such as the Super Simple Mixer) should not be able to “influence” the low impedance outputs (such as in Hagiwo’s designs) of modules plugged into it. If the outputs really are being changed by the mixer then something has been built wrong.
Two mixer channels can cancel each other though, if the inputs are the same amplitude and opposite sign. That’s just how mixing works, and there’s not much to be done about it other than to invert one of the signals going in.
Yes, a sort of crackling/distortion at times. Others turn quiet when certain modules are plugged into it.
I swear the Modular in a Week PWM Peaks is one of the worst offenders.
Why I wondered if it could be 5v vs 12v effecting eachother, but I guess they’re all rougly 10v peak to peak.
Was curious if anyone else had experienced something similar also.
Of course the maximum mixer output is around 20 Vpp, so if two 10 Vpp signals peak near the same time at full gain, that will be pushing the maximum, and if there are three Vpp signals they could really push the output to the limit, causing distortion. That’s if there isn’t a DC offset. With a DC offset it could get worse.
You can add capacitors to remove any DC offset on the inputs, you can turn the input pots down to make sure the output stays within range.
‘A-ha’ that could be it. It felt like they were fighting each other so this could be the cause. Every module I have probably does have different vpp as they’re all scoured from all over the internet- so its not like I can set all the levels the same on the mixer and get consistent levels (I am realising now, ‘a-ha’).
It might be obvious to some but your ‘output max 20vpp’ point made me realise that there are limits for the opamp(?). (And now I understand why some mixers have clipping indicators or VU meters)
So as a rule of thumb; it’s better to keep volume low on all the drum inputs, and then mix the vcos with those levels. Then turn the gain up after those are mixed (do you guys set the kick first in your mix? Or I guess I should start looking into this stuff myself haha)
Currently I mix all drum voices with the ‘SSM’ and then plug that into my BMC mixer clone on my other rack to listen to everything together.
If you could point me in the direction of schems to look at for the input offset capacitors if that helps?
I will now look into a clipping indicator too doh!
and some people use the clipping in a musical sense. I’ve known people to buy a specific brand of mixer because of the way it would distort when overdriven with what others would consider a too high input gain.
To summarise for anyone finding this article: don’t doubt the circuit or your soldering skills. Check your headroom and make sure your loud drums aren’t clipping.
Also check your cables- I found a faulty one today which was shorting to ground, it made modules in my case act strangely.
) The arduino drum modules I have all use pwm, could they be phasing eachother out.
doh!